Six patients with Hashimoto thyroiditis (HT) and associated encephalopathy (HE) are described and compared with 14 well-documented cases retrieved from the literature. HE typically affects patients when they are euthyroid and, in an appropriate clinical situation, antithyroid autoantibodies are the main indicators of HE. Since clinical features of HE are unspecific, other aetiologies such as infectious, metabolic, toxic, vascular, neoplastic, and paraneoplastic causes have to be excluded. Our own six cases and those from the literature show that two types of initial clinical presentation can be differentiated: a vasculitic type with stroke-like episodes and mild cognitive impairment in nine patients, and a diffuse progressive type with dementia, seizures, psychotic episodes or altered consciousness in 11 patients. These types may overlap, particularly in the long-term course without treatment. Response to steroids was usually excellent with complete remission in 80%. Eighteen of the 20 patients were women. Characteristic, though unspecific, findings were abnormal EEG (90%) and CSF (80%). Together with quantitative neuropsychological testing, these proved sensitive for monitoring the efficacy of therapy. Conversely, antithyroid autoantibody titres did not correlate with the severity or type of clinical presentation. The link between HE and HT is not clear. A pathogenetic role for antithyroid autoantibodies in the central nervous system seems unlikely.

Paramedian thalamic stroke (PTS) is a cause of organic hypersomnia, which in the absence of systematic sleep-wake studies has been attributed to disruption of ascending activating impulses and considered a "dearoused" state. However, an increasing mount of data suggests a role of the thalamus in sleep regulation and raises the possibility that a sleep disturbance contributes to hypersomnia in PTS. We evaluated 12 patients with magnetic resonance imaging-proven isolated PTS and hypersomnia with 10 to >20 hours of sleep behavior per day. Nocturnal polysomnographic findings paralleled the severity of hypersomnia. All subjects had increased stage 1 NREM sleep, reduced stage 2 NREM sleep, and reduced numbers of sleep spindles. In patients with severe hypersomnia, slow-wave (stages 3-4) NREM sleep was often reduced, but there were no major REM sleep alterations. Daytime sleep behavior was associated mostly with stage 1 sleep by electroencephalogram; there was no correlation between hypersomnia and results of nap tests. We conclude that hypersomnia following PTS is accompanied by deficient arousal during the day and insufficient spindling and slow-wave sleep production at night. These observations support the hypothesis of a dual role of the paramedian thalamus as "final common pathway' for both maintenance of wakefulness and promotion of NREM sleep.

Background-The univariate study of clinical, electrophysiological, or biochemical variables has been shown to predict the outcome in postanoxic coma in about 50% of patients for each type of variable. Previous studies did not, however, consider the prognostic accuracy of a multivariate approach. Methods-Sixty patients in coma for more than six hours after cardiac arrest were prospectively examined by means of repeated clinical examinations (including Glasgow coma score (GCS)), EEG, and medianus nerve somatosensory evoked potentials (SEPs). In 16 patients, the early concentrations of serum neuron specific enolase and ionised calcium were also measured. Results-Within the first year after cardiac arrest, 20% of patients made a good neurological recovery; 80% remained in a vegetative state or died. Clinical examination correctly predicted outcome in 58% of patients, SEP in 59%, and EEG in 41%. The combination of clinical examination, SEP, and EEG raised the percentage of correct predictions to 82%, without false pessimistic predictions. Concentrations of serum neuron specific enolase and ionised calcium were of no additional prognostic help. Multivariate regression analysis identified the association of GCS < 8 at 48 hours with abnormal or absent early cortical SEPs as highly predictive of a bad outcome (risk = 97%, 95% confidence interval = 86-99%). Conclusion-The combination of GCS at 48 hours, SEP, and if these are nonconclusive, EEG, permits a more reliable prediction of outcome in postanoxic coma than clinical examination alone.

Amplitudes of motor evoked potentials (MEPs) are usually much smaller than those of motor responses to maximal peripheral nerve stimulation, and show marked variation between normal subjects and from one stimulus to another. Consequently, amplitude measurements have low sensitivity to detect central motor conduction failures due to the broad range of normal values. Since these characteristics are mostly due to varying desynchronization of the descending action potentials, causing different degrees of phase cancellation, we applied the recently developed triple stimulation technique (TST) to study corticospinal conduction to 489 abductor digiti minimi muscles of 271 unselected patients referred for possible corticospinal dysfunction. The TST allows resynchronization of the MEP, and thereby a quantification of the proportion of motor units activated by the transcranial stimulus. TST results were compared with those of conventional MEPs. In 212 of 489 sides, abnormal TST responses suggested conduction failure of various degrees. By contrast, conventional MEPs detected conduction failures in only 77 of 489 sides. The TST was therefore 2.75 times more sensitive than conventional MEPs in disclosing corticospinal conduction failures. When the results of the TST and conventional MEPs were combined, 225 sides were abnormal: 145 sides showed central conduction failure, 13 sides central conduction slowing and 67 sides both conduction failure and slowing. It is concluded that the TST is a valuable addition to the study of MEPs, since it improves detection and gives quantitative information on central conduction failure, an abnormality which appears to be much more frequent than conduction slowing. This new technique will be useful in following the natural course and the benefit of treatments in disorders affecting central motor conduction.

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